Methods are known for fluorinating unsaturated organic compounds by using elemental fluorine. Fluorinating the double bond is a reaction presenting strong difficulties in practical implementation, due to its highly exothermal character, with the evolution of high amounts of heat, of the order of 107 kcal per each double bond. The high reaction energy can lead to strong increases of the reaction mass temperature, within very short times, and hence difficult to control. Locally the temperature can be so high as to cause the breakage of C--C bonds in the product, with the degradation of the same, and the formation of undesired byproducts. Another occurring drawback is the dimerization of the product.
In the processes of the prior art, obviating these drawbacks and dangers has been tried by carrying out the fluorinating reaction under easily controllable conditions: the most common contrivances are the use of very low reaction temperatures, even as low as -120.degree. C., in particular at the beginning of the process, and/or the use of low concentrations of fluorine, which to that purpose is diluted with such inert gases as nitrogen or noble gases (helium).
These contrivances suffer however from some drawbacks: first of all, they extremely reduce the reaction rate, and furthermore, sometimes, the use of low-reactivity conditions does not allow the reaction to be conveniently carried out and consequently, when said reaction, after an initial induction time, starts, the amount of fluorine present in the reaction mixture is higherthan its optimum value and can lead to a too fast and uncontrollable reaction.